s390/mm: use TASK_MAX_SIZE where applicable

To improve readability we can use TASK_MAX_SIZE when we just check for the
upper limit.  All places explicitly dealing with 3 vs 4 level pgtables
were left unchanged.
Signed-off-by: Dominik Dingel <dingel@linux.vnet.ibm.com>
Reviewed-By: Sascha Silbe <silbe@linux.vnet.ibm.com>

arch/s390/mm/mmap.c

@@ -169,12 +169,12 @@ arch_get_unmapped_area_topdown(struct file *filp, const unsigned long addr0,
 
 int s390_mmap_check(unsigned long addr, unsigned long len, unsigned long flags)
 {
-	if (is_compat_task() || (TASK_SIZE >= (1UL << 53)))
+	if (is_compat_task() || TASK_SIZE >= TASK_MAX_SIZE)
 		return 0;
 	if (!(flags & MAP_FIXED))
 		addr = 0;
 	if ((addr + len) >= TASK_SIZE)
-		return crst_table_upgrade(current->mm, 1UL << 53);
+		return crst_table_upgrade(current->mm, TASK_MAX_SIZE);
 	return 0;
 }
 
@@ -189,9 +189,9 @@ s390_get_unmapped_area(struct file *filp, unsigned long addr,
 	area = arch_get_unmapped_area(filp, addr, len, pgoff, flags);
 	if (!(area & ~PAGE_MASK))
 		return area;
-	if (area == -ENOMEM && !is_compat_task() && TASK_SIZE < (1UL << 53)) {
+	if (area == -ENOMEM && !is_compat_task() && TASK_SIZE < TASK_MAX_SIZE) {
 		/* Upgrade the page table to 4 levels and retry. */
-		rc = crst_table_upgrade(mm, 1UL << 53);
+		rc = crst_table_upgrade(mm, TASK_MAX_SIZE);
 		if (rc)
 			return (unsigned long) rc;
 		area = arch_get_unmapped_area(filp, addr, len, pgoff, flags);
@@ -211,9 +211,9 @@ s390_get_unmapped_area_topdown(struct file *filp, const unsigned long addr,
 	area = arch_get_unmapped_area_topdown(filp, addr, len, pgoff, flags);
 	if (!(area & ~PAGE_MASK))
 		return area;
-	if (area == -ENOMEM && !is_compat_task() && TASK_SIZE < (1UL << 53)) {
+	if (area == -ENOMEM && !is_compat_task() && TASK_SIZE < TASK_MAX_SIZE) {
 		/* Upgrade the page table to 4 levels and retry. */
-		rc = crst_table_upgrade(mm, 1UL << 53);
+		rc = crst_table_upgrade(mm, TASK_MAX_SIZE);
 		if (rc)
 			return (unsigned long) rc;
 		area = arch_get_unmapped_area_topdown(filp, addr, len,

arch/s390/mm/pgtable.c

@@ -55,7 +55,7 @@ int crst_table_upgrade(struct mm_struct *mm, unsigned long limit)
 	unsigned long entry;
 	int flush;
 
-	BUG_ON(limit > (1UL << 53));
+	BUG_ON(limit > TASK_MAX_SIZE);
 	flush = 0;
 repeat:
 	table = crst_table_alloc(mm);